The present invention generally relates to communication terminal connection systems, and more particularly to a communication terminal connection system which connects a terminal which is designed for a low-speed communication and a terminal which is designed for a high-speed communication. The communication terminal connection system provides a degree of freedom in making a connection between a terminal and a multiplexer which multiplexes communication data from the terminal and outputs multiplexed communication data to a high-speed line.
In order to reduce an integrated services digital network (ISDN) to practice, multiplexers in conformance with the CCITT recommendations V.120 are being developed. The multiplexer (or terminal adaptor) multiplexes communication data from terminals which are designed for a low-speed communication and outputs a multiplexed communication data to a high-speed line such as a public line. In order to improve the practical functions of such a multiplexer, there is a need to improve the method of connecting the terminals and the multiplexer.
As described above, the multiplexer of an ISDN interface multiplexes the communication data from the terminals and outputs the multiplexed communication data to the high-speed line. FIG.1 shows one conventional method of connecting a multiplexer 2 on a transmission side and a multiplexer 2 on a reception side. A plurality of terminals 1 which are designed for low-speed communication are connected to the multiplexers 2. Each multiplexer 2 is connected to a public line network 4 via a public line 3a.
FIG.2 shows another conventional method of connecting a plurality of multiplexers 2 on the transmission side and the multiplexer 2 on the reception side. A private branch exchange 5 is provided between the multiplexers 2 on the transmission side and the public line 3a. One of the multiplexers 2 on the transmission side 15 connected to the public line 3a depending on a switching process of the private branch exchange 5.
But according to these conventional connecting methods, the terminal 1 and the multiplexer 2 are directly connected by a cable, and the connection between the terminal 1 and the multiplexer 2 is semi-fixed. For this reason, there is a problem in that the connection of the cable must be changed or a new multiplexer 2 must be provided when a terminal 1 needs to be newly connected. Moreover, there is a limit to the length of the cable which connects the terminal 1 and the multiplexer 2 when the signal attenuation is taken into account. For example, the length of the cable is limited to approximately 15 m in the case of the RS-232C standards. Hence, there is also a problem in that the terminals 1 which can use one multiplexer 2 in common must be arranged within a predetermined distance from each other. Furthermore, according to the conventional connecting method which uses the private branch exchange 5, there is a problem in that even when the multiplexer 2 is connected to a desired destination, a terminal 1 which is not connected to this multiplexer 2 cannot use the line to connect which is the desired destination.